Device for sealing gap between electrode and lining of electric arc furnace

ABSTRACT

A sealing device for the gap between an electrode and a lining of an electric furnace comprises a chamber through which the electrode passes. This chamber is supplied with an inert gas under pressure from the holes of at least two curved headers which form a ring around the electrode. Installed between the headers and the part of the chamber through which the electrode passes are vanes which form identical acute angles with a respective radius drawn from the center of the chamber to the base of each vane, for creating a circular flow of the inert gas around the electrode. As a result, a gas flow is created near the electrode, preventing escape of gases from the furnace into the atmosphere.

United States Patent Frolov et al. 1451 Oct, 10, 1972 [54] DEVICE FOR SEALING GAP BE I'WEEN 2,405,236 8/1946 Rhoades et al. ..13/17 ELECTRODE AND LINING 0F 2,769,079 10/1956 Briggs....................2l9/121 P ELECTRIC ARC FURNACE 2,865,972 12/1958 Augsburger ..13/ 17 [72] Inventors: y Fedomvich Fmov p p K 3,042,830 7/1962 Orbach ..219/ 121 P X Marxa, 8/21, kv. 70; [van Petrovieh FOREIGN PATENTS OR APPLICATIONS 161,792 4/1964 U.S.S.R. ..13/17 Basalaev ulitsa Rimsko o-Korsakova, 9/1, kv. 5; Jury Dmiirievich Pnmary i9 Mayqwsky Mm ulitsa Pamirskaya 100/1 Attorney-Waters, Rodin, Schwartz & Nissen kv. 4; Viktor Valerjanovich Golikov, ulitsa Novogodnyaya, 20, kv. 54, all [57] ABSTRACT of Novosibirsk, U.S.S.R. A sealing device for the gap between an electrode and a lining of an electric furnace comprises a chamber [22] Ffled' March 161970 througi which the electrode passes. This chamber is [21] App1.No.: 19,839 supplied with an inert gas under pressure from the holes of at least two curved headers which form a ring around the electrode. Installed between the headers ..13/17,13/15,I )g) l 2 and the part of the chamber through which the elec "ode passes are vanes which form identical acute am [58] Field of Search gles with a respective radius drawn from the center of the chamber to the base of each vane, for creating a circular flow of the inert gas around the electrode. As [56] Reerences Cited a result, a gas flow is created near the electrode, n STATES PATENTS preventing escape of gases from the furnace into the atmos here. 1,129.37? 2/1915 Bronn etal. ..13/17x p 1,732,431 10/1929 Bruggmann ..13/17 13 Chains, 3 Drawing Figures PATENTEUnm 10 m2 SHEEI 1 BF 3 PATENTEI] URI 1 0 I972 SHEET 3 0F 3 Fill-3.5

DEVICE FOR SEALING GAP BETWEEN ELECTRODE AND LINING F ELECTRIC ARC FURNACE The present invention relates to electric arc furnaces and more specifically it relates to a device for sealing the gaps between the electrodes and linings of said furnaces.

The device according to the invention can be used for sealing the gaps between the furnace lining and the pipes for loading the charge and discharging the gases.

Known in the art is a device for sealing the gap between the electrode and the roof of the electric arc furnace comprising a chamber installed on the furnace roof above the hole for the electrode. The electrode passes through this chamber. The lower flat surface of the chamber is freely installed on the framing of said hole. The chamber is filled under pressure with a jet of air or nitrogen through a pipe passing through the external cylindrical wall of the chamber and this air or nitrogen prevents the gases from escaping from the furnace. Between the electrode and the holes in the upper and lower parts of the chamber, through which the electrode passes, there are circular gaps (see, for example, the USSR Pat. No. 161792, Cl 18b /52, 1964).

The difficulties arising in the use of this sealing device are caused by a large consumption of air or nitrogen supplied into the chamber of the device because the gas is not only supplied into the working space of the furnace through the circular gap between the electrode and the wall of the hole in the furnace roof, but also escapes outside through the unsealed circular gap between the electrode and the upper part of the chamber.

Moreover, the air or nitrogen is admitted into the chamber at one point and, consequently, is not distributed evenly and at the same pressure over the chamber around the electrode which impairs the quality of the seal. At the same time, free installation of the chamber on the framing of the hole for the electrode does not exclude partial escape of gases from the furnace which becomes particularly dangerous if these gases are toxic. Absence of the cooling system in the device which operates on a hot furnace roof leads to a necessity for the frequent replacement of its parts.

Also well known in the art is a device for sealing the gap between the electrode and the roof of the electric arc furnace which comprises a watercooled cylindrical chamber whose space is open towards the electrode, said chamber being also installed on the framing of the hole for the electrode in the furnace roof. The chamber is filled with a neutral gas supplied under pressure from above.

Then the gas is pumped out from the lower part of the chamber. To reduce the amount of the neutral gas escaping from the chamber, the upper part of the chamber, located far from the furnace roof, is provided with a seal made of a fibrous material. This device, however, is very complicated. It is very high so that the working end of the electrode has to be lengthened. This impairs the electrical characteristics of the furnace. At a relatively high consumption of neutral gas, the latter is irregularly distributed over the chamber. The gasdischarge pipe must be carefully sealed especially in the furnaces liberating toxic gases. In the reduction furnaces for volatile metals it happens that the metal vapors a are condensed in the cooled chamber and in the gas-discharge pipes.

An object of the present invention is to eliminate the aforesaid disadvantages.

The main object of the invention resides in providing such a device for sealing the gap between the electrode and lining of an electric arc furnace which will prevent the gases from penetrating into the sealing device from the furnace and further into he atmosphere.

This object is accomplished with the aid of a device for sealing the gap between the electrode and lining of an electric arc fumace comprising a chamber through which the electrode passes, said chamber being connected with a mechanism which supplies an inert gas under pressure into this chamber wherein, according to the invention, the inert gas is fed into the chamber through at least two arched headers with gas outlet holes, said headers forming a ring around the electrode; located between the headers and the parts of the chamber accommodating the electrode are vanes, each of which, together with the radius drawn from the center of the chamber towards the vane base, forms an acute angle required for forcing the inert gas to move in a circular direction around the electrode.

This construction of the sealing device ensures a uniform distribution of the inert gas over the chamber; the directional movement of the inert gas creates a rotating gas ring or screen around the electrode, this screen preventing the gases from escaping from the furnace into the sealing device and further, into the atmosphere.

In a preferable embodiment of the device according to the invention, it is practicable that the header be located inside the chamber. This simplifies the manufacture, installation and operation of the sealing device.

It is also practicable that the vanes be made curvilinear. This will ensure the most effective motion of the gas jets discharged from the header holes.

It is expedient that the sealing device be cooled with water in order to ensure its serviceability and long life under the conditions of high temperatures prevailing on the external surface of the furnace lining.

It is practicable that at its flat wall which is farthest from the lining, the chamber is provided with radially movable sheet segments whose ends interacting with the electrode are fitted with vertical shoes whose ends are preferably bent inward, into the chamber. It is practicable that the segments be loaded with a force directed towards the middle of the chamber where the electrode passes through. The provision of segments in combination with the vanes and with the lower wall of the chamber located near the lining forms passages for directing the inert gas from the headers to the electrode surface and assists in the flow of the inert gas along the electrode towards the hole in the lining for the electrode. The fact that the segments are abutting against the electrode surface promotes the pressuretightness of the seal and cuts down the consumption of the inert gas. Besides, the segments clean the electrode surface additionally which raises the efficiency of the device. The shoes with curved ends prevent jamming of the segments on the electrode joints. Loading of the segments with a constant force contributes to their constant contact with the electrode.

It is practicable that the ends of the sheet segments which are farthest from the middle part of the chamber be brought outside through the slots in the cylindrical wall of the chamber. In this case the simplest are the mechanisms which interact with these ends of the segments and load them with a force directed towards the middle part of the chamber intended for the accommodation of the electrode.

It is practicable that the gaps between the ends of the sheet segments protruding outside, and the slots in the cylindrical wall of the chamber be sealed with, e.g., a mechanical seal made of an elastic material. This will prevent leakage through this gap, of the inert gas supplied into the chamber thereby reducing its total consumption.

It is practicable that the ends of the sheet segments protruding outside be connected to the mechanisms which press them against the electrode. The simplest are the lever-tape mechanisms secured in the chamber and loaded by counterweights. In addition to the simplicity of construction, this ensures a constant contact of the segments with the electrode and the efficiency of the sealing device.

It is practicable that the flat wall of the chamber which is farthest from the lining be mounted with an additional cooled gland packing. This packing will prevent the leaks of the inert gas which may seep between the segments and the electrode, and increase the efficiency of the sealing device.

To prevent the material of the additional gland packing from being pulled from the device when the electrode moves in the operating furnace, it is practicable to impose a load on the gland packing.

To reduce the pressure of the inert gas it is expedient that the outlet holes of the header be directed towards the hole for the electrode in the flat wall of the chamber adjoining the furnace lining.

A substantial advantage of the present invention resides in completely preventing the escape of the furnace gases into the atmosphere through the gap between the electrode and the walls of the hole in the lining intended for inserting the electrode into the furnace.

Now the invention will the described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a longitudinal section of the device according to the invention;

FIG. 2 is a section taken along line II-II of FIG. 1;

FIG. 3 is a section taken along line III-III of FIG. 1.

The device for sealing the gap between the electrode and lining of an electric arc furnace comprises a hollow chamber consisting of a lower flat wall 2 adjoining the lining (FIG. 1), said wall being farthest from the lining 1, an upper wall 3, and a cylindrical vertical wall 4. The lower wall 2 and the cylindrical wall 4 are rigidly interconnected by welding. An electrode 5 passes through the middle part of the chamber.

To facilitate the installation, the chamber is made in two halves. The connecting flanges 6 (FIGS. 2,3) welded to the lower walls 2 and cylindrical walls 4 are secured to each other after installation, around the electrode 5, by bolts 7 (though wedges may also be used). Depending on the diameter of the electrode 5 which affects the overall dimensions and weight of the sealing device, the chamber may be made of more than two parts.

Located inside the chamber on the flat wall 2 are two semi-circular or arched headers 8 (FIG. 1) forming a ring around the electrode 5. The ends of the headers 8 are closed by plugs 9 (FIG. 2). Each header is provided with an inlet pipe 10 (FIGS. 1, 2, 3) one end of which is rigidly secured in the hole of the header wall, said hole being made on the outside, in the middle of the header length. The second end of the header 10 passes through a hole in the cylindrical wall 4 outside of the chamber where it is connected to a mechanism (not shown) which supplies inert gas under presure into the header 8. The inner walls of the headers 8 have holes 11 (FIG. 2) directed towards the middle part of the chamber; through these holes the inert gas is discharged into the chamber.

The supply of the inert gas into the chamber from the headers 8 which form a ring around the electrode 5, ensures uniform delivery and distribution of said gas over the periphery of the electrode.

Installed between the headers 8 and the part of the chamber through which the electrode passes are vanes 12 (FIG. 1). The vanes 12 are installed so that, together with imaginary radiuses drawn from the center of the chamber to the base of each vane, they form identical acute angles for creating a directional circular flow of the inert gas around the electrode.

Due to such an installation of the vanes 12, the jets of the inert gas flowing from the holes 11 form a circular screen around the electrode 5, said screen preventing the furnace gases from penetrating into the sealing device and, consequently, into the atmosphere.

For better direction of the gas jets flowing from the holes II in the headers 8, and for improving the aerodynamic characteristics of the moving gas jets the vanes 12 are made curvilinear. For reducing the pressure of the inert gas, the holes 11 are directed towards the outlet in the lower wall of the chamber for the electrode.

To increase the durability of the chamber under the efiect of a considerable radiation of heat from the lining 1, the chamber has a cooling system for which purpose the external surface of the wall 2 is provided with a welded box 13 through which cooling water is circulated. The water is delivered into the box through a pipe connection 14 (FIGS. 2, 3) and is discharged from it through a pipe connection 15. To ensure the circulation of water through the boxes 13 (their number being equal to that of the component parts of the chamber wall 2, they are interconnected by a pipe 16.

Located in the chamber above the headers 8 and the vanes 12 at the upper flat wall 3 which is farthest from the lining l are radially movable sheet segments 17 (FIG. 1) resting on the vanes 12 and supports 18 mounted inside the chamber between the cylindrical wall 4 and the headers 8. The inner ends of the sheet segments 17 proximate the electrode 5 are fitted with shoes 19 located in cutouts in wall 3, the ends of said shoes being bent inward, into the chamber.

The sheet segments 17 together with the vanes 12 and the lower wall 2 of the chamber form passages for the gas jets flowing from holes 11 which assists in the directional flow of the inert gas from the headers 8 to the electrode 5.

The ends 20 (FIG. 3) of the sheet segments 17 which are farthest from the middle part of the chamber, pass outside through cutouts in the cylindrical wall 4 where they engage levers 21 (FIG. 1) which are articulated to supports 22, the latter being secured to the upper part of the chamber.

To ensure a constant contact of the sheet segments 17 against the electrode 5, the levers 21 are loaded with adjustable counterweights 23 whose position on the levers 21 is fixed with the aid of pins 24 or other suitable retainers.

A constant contact of the sheet segments against the electrode ensures the flow of the inert gas from the chamber only into the furnace through the gap between the electrode and the walls of the hole in the line designed for inserting the electrode into the furnace.

The segments additionally clean the surface of the electrode.

Mounted externally on the chamber, on the upper flat wall 3 which is furthest from the lining l, is a packing gland comprising a cooled box 25 fitted around the electrode 5, the inner wall of said box forming a funnel for accommodating an elastic packing material 26 which rests on the sheet segments 17. Cooling water circulates through the box 25.

On top, the packing material 26 of the gland is loaded by weights 27 which are centered in relation to the gland by rods 28 secured on the box 25.

Placing a load on packing material 27 of the additional gland improves the serviceability of the gland and improves the scaling properties of the device.

To improve the pressuretightness of the seal, the points where the inlet pipe connection and the protruding ends of the sheet segments pass through the cylindrical wall I are sealed with glands 29 (FIG. 3) while the joints of the chamber between the flanges 6 are provided with sealing gaskets 30. The joints between the upper wall 3 of the chamber and the vertical cylindrical wall 4 are provided with sealing gaskets (not shown in the drawing).

The sheet segments 17, the additional gland 26 above the chamber and the packing glands 29 at the points where the pipe connections 10 and the ends 20 of the sheet segments 17 pass outside through the cylindrical wall 4 of the chamber completely prevent leaks of the inert gas from the chamber which reduces its consumption and ensures a high degree of pressuretightness of the sealing device.

The box 13 of the sealing device is tightly embedded into the lining l.

in the operating service, the inert gas is supplied under pressure from a gas source (not shown) through the pipe connections 10 into the headers 8. From the headers 8, the gas flows as jets through the holes 11 in the header walls directed towards the middle part of the lower wall 2 of the chamber. To ensure a uniform discharge of the gas jets and create a uniform gas flow around the electrode, the nominal bores of the holes 11 are increased gradually as they are located farther from the central part of the header 8 (Le. from the point where the inert gas is delivered into the header 8).

Emerging from the holes ll, the gas jets flow into the passages formed by the vanes 12, the lower wall 2 of the chamber and by the sheet segments 17, and are directed towards the middle part of the chamber, towards the electrode 5. The arrangement and shape of the vanes 12 contribute to the creation of a rotating ring around the electrode 5, this ring constituting an inert gas screen under pressure.

from the chamber into the gap, the inert gas forces out the furnace gases from the zone of the hole for the electrode in the lining 1, thereby sealing the gap between the electrode 5 and the lining l.

[f the fastening of the sealing device in the lining 1 becomes damaged in operation for some reason, the furnace gases will not escape. In this case part of the inert gas flowing along the electrode 5 from the chamber into the furnace will arrive under pressure into the fastening unit, around the box 13, which will prevent penetration of the gases from the furnace into the atmosphere.

If the electrode 5 is made up of a number of sections, it may happen that they are joined eccentrically, with a step at the point of the joint. When the joint passes through the sheet segments 17, the step comes in contact with the curved ends of the shoes 19, slides along them and forces the segments 17 apart which precludes their jamming at the joints between the sections of the electrode 5, and breaking of both the electrode and the sealing device.

The material of the gland 26 is prevented from being clamped and pulled into the chamber during the downward travel of the electrode by the sheet segments 17 pressured tightly against the electrode 5; the movement of the gland material 26 outward is prevented by the load 27 placed on top of it and centered by the rods 28.

A constant pressure of the sheet segments 17 on the electrode 5 is ensured because their ends 20 which are farthest from the middle part of the chamber and protrude outside, interact with the levers 21; these levers are loaded by the counterweights 23 which apply a force to the segments 17, this force being directed towards the middle part of the chamber intended for the insertion of the electrode 5. The value of this force can be adjusted by changing the position of the counterweight 23 on the lever 21. The selected position of the counterweight 23 is fixed by the pins 24 secured in the holes on the lever 21.

The mechanism for pressing the segments 17 against the electrode may be of a spring-type acting directly on the sheet segment 17. Such a mechanism can be installed either inside or outside the chamber.

The provision of a water cooling system for the device preserves its mechanical strength and rigidity of all the elements of the device operating at a high heat radiated by the furnace lining. Additionally, the packing material of the gland is prevented from buming thereby improving the sealing properties and serviceability of the glands, and preventing the leakage of the inert gas into the atmosphere, i.e. ensuring a minimum consumption of the inert gas.

We claim:

I. A device for sealing a gap formed between a wall of an electric arc furnace and an electrode which passes with clearance in a hole in the wall, said device comprising a cylindrical chamber tightly mounted on the wall of the furnace and defininga central opening through which the electrode can pass, at least two curved headers mounted in said chamber and defining a ring around the electrode. means for delivering an inert gas under pressure into said headers, said headers having an inner wall facing the electrode and being pro vided with holes through which the inert gas can flow towards the electrode, a plurality of spaced vanes in said chamber extending inwardly from the inner walls of the headers to a position proximate the electrode, adjacent vanes defining a passageway for travel of the inert gas from a respective hole towards the electrode, said vanes each forming an acute angle with a radial line drawn from the center of the chamber to the juncture of the vane and the inner wall of the associated header to induce a circular flow of the inert gas around the electrode and thereby seal the gap between the wall of the furnace and the electrode.

2. A device according to claim 1 wherein said vanes are curvilinear.

3. A device according to claim 2 comprising means for cooling said chamber.

4. A device according to claim 1 comprising sheet segments mounted in said chamber and having inner ends proximate said electrode for engagement therewith, shoes on said inner ends of the segments for contact with the electrode, said shoes having ends which are bent inwardly into said chamber; and means urging said segments against the electrode.

5. A device according to claim 4 wherein said sheet segments have ends remote from the electrode and which pass through cutouts yluYIUeCl m the cylindrical wall of said chamber.

6. A device according to claim 5 comprising packing glands sealing said ends of said sheet segments which pass from said chamber through the cutouts in said cylindrical wall.

7. A device according to claim 6 wherein said means urging the sheet segments against the electrode comprises levers engaging the ends of said sheet segments passing through said cylindrical wall of said chamber, and counterweights applying load to said levers.

8. A device according to claim I wherein said chamber has a flat wall which is farthest from said lining, and comprising an external packing gland on said flat wall of the chamber.

9. A device according to claim 8 comprising means applying force to said packing gland.

10. A device according to claim 8 comprising means for cooling said packing gland.

11. A device according to claim 1 wherein said means for delivering an inert gas into the headers comprises an inlet conduit coupled to each header, said holes in the inner wall of the header being increased in size the further their disposition from said inlet conduit to provide uniform flow to the passageways between the vanes.

12. A device according to claim 1 comprising a coo|- ing means interposed between said chamber and the wall of the furnace.

13. A device according to claim 1 wherein said electrode travels vertically and said chamber is horizontal and above the wall of the furnace. 

1. A device for sealing a gap formed between a wall of an electric arc furnace and an electrode which passes with clearance in a hole in the wall, said device comprising a cylindrical chamber tightly mounted on the wall of the furnace and defining a central opening through which the electrode can pass, at least two curved headers mounted in said chamber and defining a ring around the electrode, means for delivering an inert gas under pressure into said headers, said headers having an inner wall facing the electrode and being provided with holes through which the inert gas can flow towards the electrode, a plurality of spaced vanes in said chamber extending inwardly from the inner walls of the headers to a position proximate the electrode, adjacent vanes defining a passageway for travel of the inert gas from a respective hole towards the electrode, said vanes each forming an acute angle with a radial line drawn from the center of the chamber to the juncture of the vane and the inner wall of the associated header to induce a circular flow of the inert gas around the electrode and thereby seal the gap between the wall of the furnace and the electrode.
 2. A device according to claim 1 wherein said vanes are curvilinear.
 3. A device according to claim 2 comprising means for cooling said chamber.
 4. A device according to claim 1 comprising sheet segments mounted in said chamber and having inner ends proximate said electrode for engagement therewith, shoes on said inner ends of the segments for contact with the electrode, said shoes having ends which are bent inwardly into said chamber; and means urging said segments against the electrode.
 5. A device according to claim 4 wherein said sheet segments have ends remote from the electrode and which pass through cutouts provided in the cylindrical wall of said chamber.
 6. A device according to claim 5 comprising packing glands sealing said ends of said sheet segments which pass from said chamber through the cutouts in said cylindrical wall.
 7. A device according to claim 6 wherein said means urging the sheet segments against the electrode comprises levers engaging the ends of said sheet segments passing through said cylindrical wall of said chamber, and counterweights applying load to said levers.
 8. A device according to claim 1 wherein said chamber has a flat wall which is farthest from said lining, and comprising an external packing gland on said flat wall of the chamber.
 9. A device according to claim 8 comprising means applying force to said packing gland.
 10. A device according to claim 8 comprising means for cooling said packing gland.
 11. A device according to claim 1 wherein said means for delivering an inert gas into the headers comprises an inlet conduit coupled to each header, said holes in the inner wall of the header being increased in size the further their disposition from said inlet conduit to provide uniform flow to the passageways between the vanes.
 12. A device according to claim 1 comprising a cooling means interposed between said chamber and the wall of the furnace.
 13. A device according to claim 1 wherein said electrode travels vertically and said chamber is horizontal and above the wall of the furnace. 